1. Field of the Invention
The present invention relates to a differential coding circuit such as a differential pulse code modulation (DPCM) coder which operates at a high speed.
The differential coding circuit according to the present invention can be used, for example, as a device which effects bandwidth compression coding of a picture signal.
2. Description of the Related Art
A differential coding circuit of the prior art, as described later in more detail, includes, for example, a subtractor for calculating a differential signal between a sampled input signal and a predicted signal, a quantizer for quantizing the differential signal, an adder for adding a quantized differential signal from the quantizer and a predicted signal before one sampling period, and a multiplier for multiplying an output signal of the adder by a prediction coefficient so as to generate the predicted signal. When used as a picture bandwidth compression coding device, however, the speed of operation is not as high as desired.